This invention relates to methods and apparatus for making "man made" snow and, in particular, to a new and improved method and apparatus for forming ice crystals for seeding water droplets in an air-water mixture generated in any apparatus for making snow.
The various techniques used for making "man made" snow in ski areas all rely on a mixture of water and air to form small ice crystals or snow flakes which have some of the characteristics of naturally occuring snow. In most, if not all cases, the techniques employed are not capable of making usable snow at temperatures at or near freezing without the introduction of nucleation sites around which freezing begins. This is due to a well-known phenomenon, whereby water droplets will not freeze, even at temperatures well below freezing, until the first ice crystal forms or is introduced. As soon as the first few crystals form, the freezing proceeds extremely rapidly. In snow making, guns where new water droplets are being constantly introduced, it is necessary to introduce necleation sites to trigger the snow making action if the ambient temperature is between 0.degree. and 32.degree. F. The most effective nucleation site is an ice crystal. There are also various substances that can substitute for the ice crystals to act as catalysts, but this introduces a third substance in addition to the water and air.
The most effective and efficient way to introduce these ice crystals or nucleation sites is by a so-called nucleator which utilizes only water and air. The nucleator produces smaller particles than a convential air/water gun because the key components are smaller in size and higher ratios of air to water are used. The nucleator is generally capable of making ice crystals at much higher temperatures than a basic air/water gun itself. The nucleator is located near the exit of the air/water of fan gun, so that the ice crystals are projected into the plume from the gun at an acute angle. For snow making devices where ice nuclei are not otherwise produced the results of this action are drammatic at temperatures at, or even slightly above freezing. When the nucleator is shut off the gun makes nothing but wet spray; when the nucleator turned on the gun it immediately starts making good snow.
There are a number of types of nucleators currently available, and in the case of the large fan type guns, as many as eight nucleators are used with each gun. However, all nucleators heretofore available require air pressure of 70 psig or greater to operate satisfactorily.
Recently, a new snow making gun has been developed which operates with an air pressure at or near 30 psig instead of 80 to 100 psig typical of all other air/water guns heretofore available. Low pressure operation has the advantage of reducing the energy cost for compressing the air to each unit to a fraction of the cost of operating conventional machines. But under some conditions, the low pressure gun, like the fan type machines, need a nucleator to initiate freezing of the water particles. Since no low pressure nucleators have been heretofore available, the use of a conventional nucleator would require a separate source of 80 psig air, as does fan gun, which greatly complicates and adds significant costs to the system.
Bearing in mind the foregoing and other deficiencies of the prior art, it is a primary object of the present invention to provide a new and improved method and apparatus for forming ice crystals for seeding water particles in snow making devices, which method and apparatus operates at significantly lower air pressures relative to prior nucleator design pressure.
It is a further object of the present invention to provide a method and apparatus for making tiny ice crystals (nuclei) which enhances the cooling effect of the compressed air on the tiny water droplets which formed therein.
It is a further object of this invention to provide a method and apparatus for making ice crystals which enhances the atomization of water droplets to produce the very small water and subsequently ice particles (nuclei).
It is another object of this invention to provide apparatus for making ice crystals which allows maximum internal flow and avoids erosion of internal parts.
It is yet another object of this invention to provide apparatus for making ice crystals which readily and easily installed and aligned on existing snow making apparatus.
It is still a further object of this invention to provide apparatus for making tiny ice crystals (nuclei) which is small in size, light in weight and includes easily interchangeable parts.
It is an important feature of this invention to develop small water droplets of a proper size and velocity to interact with low pressure as to form ice particles, which will provide nucleation sites.
Other objects will be in part, obvious and in part, pointed out in more detail hereinafter.
A better understanding of the objects, advantages, features, properties and relations of the invention will be obtained from the following detailed description and accompanying drawing which set forth an illustrative embodiment and is indicative of the way in which the principle of the invention is employed.